1. Field of the Invention
The present invention relates to an optical apparatus, such as a digital camera, video camera, etc., having an integral lens, and an interchangeable lens apparatus that can be mounted to such a camera.
2. Description of the Related Art
A so-called rear focus (inner focus) zoom lens, having a variable power lens, and a focus lens which is positioned at the image plane side of the variable power lens and performs focusing and compensation of the image plane variation that accompanies the movement of the variable power lens (function of a compensator), is provided integrally in a digital camera, video camera, or other image-taking apparatus or is used as an interchangeable lens.
For example, with a lens apparatus that uses an above-described rear focus zoom lens of an interchangeable type, focus adjustment is performed by driving the focus lens based on a focus drive signal from the camera side. Also, zooming is performed by driving the variable power lens based on a zoom drive signal resulting from the operation of a zoom switch provided at the camera and driving the focus lens so as to compensate for the image plane variation that accompanies the power variation.
Here, in order to improve the operability for image taking, image-taking apparatuses and lens apparatuses of structures with which an operator performs focusing and zooming operation by manual operation, have been proposed.
In Japanese Patent Application Laid-open No. H6 (1994)-186467, an image-taking apparatus with a structure using an optical system of the above-described rear focus zoom type and enabling manual focusing is proposed. In this image-taking apparatus, a focus lens drive motor is driven in accordance with the rotation operation of a manual focus ring to move a focus lens. Also, when the focus lens is moved during an autofocus action, the manual focus ring is rotated by a motor.
A method for indicating the distance to an object by means of a printing of distance indications on the outer circumference of the manual focus ring and a mark on a fixed part is also proposed in this Publication.
An image-taking apparatus with a structure using an optical system of the rear focus zoom type and enabling manual focus operation is also proposed in Japanese Patent Application Laid-open No. H10 (1998)-191141. In this image-taking apparatus, a manual zoom lever is operated rotatingly and a zoom lens is moved in accordance with this rotating operation. Also, the manual zoom lever is rotated by a motor when the zoom lens is moved by operation of a zoom key at the camera.
A method for indication of focal lengths by means of a scale for focal lengths on a fixed part near the manual zoom lever is also proposed in this Publication.
In Japanese Patent Application Laid-open No. H9 (1997)-304679, an image-taking apparatus with a structure, which uses an optical system of the above-described rear focus zoom type, enables manual zooming or manual focusing, and with which the driving force of a motor is transmitted via a clutch mechanism to a manual ring, is proposed. In this image-taking apparatus, selection between manual operation and motor drive of the manual ring is enabled by switching the clutch mechanism.
However, in the image-taking apparatus proposed in the above-described Japanese Patent Application Laid-open No. H6 (1994)-186467, there is the problem that during the autofocus action, the correspondence between the position to which the focus lens is moved and the position to which the manual focus ring is moved (rotated) by motor drive is not matched (not maintained).
Also, in the image-taking apparatus proposed in the above-described Japanese Patent Application Laid-open No. H10 (1998)-191141, there is the problem that during movement of the zoom lens by operation of the zoom key, the correspondence between the position to which the zoom lens is moved and the position to which the manual zoom lever is moved (rotated) by motor drive is not matched (not maintained).
Generally, with a manual operating member (manual focus ring, manual zoom ring, etc.), a viscous material, such as grease, etc., is provided between the manual operating member and a fixed member so that an operator is provided with a predetermined operating sensation (rotational torque). However, with a temperature change, the viscosity of this viscous material varies, the load varies accordingly, and thus the movement (rotation) speed of the manual operating member varies to give rise to the above-described problems.
Also, if during movement of the focus lens by the autofocus action or movement of the zoom lens by the zoom key operation, the movement of the manual operating member (ring or lever) is restrained by the operator, the movement (rotation) of the manual operating member will be limited. The problem that the correspondence between the position to which the focus lens or zoom lens is moved and the position of the manual operating member is not matched (is not maintained) occurs in this case as well.
Likewise with the image-taking apparatus proposed in the above-described Japanese Patent Application Laid-open No. H9 (1997)-304679, there is the problem that the correspondence between the position to which the focus lens or the zoom lens is moved by autofocusing or zoom key operation and the manual ring is not matched.
In the image-taking apparatus proposed in the above-described Japanese Patent Application Laid-open No. H9 (1997)-304679, in the state in which the clutch mechanism is switched to the manual operation side, that is, in the state in which the driving force is not transmitted to the manual ring, the lens will not move even if the motor is driven for autofocusing or for zooming in accordance with a zoom key operation. The motor thus practically idles (the motor rotates without the driving force being transmitted to the manual ring) and power (battery) is consumed wastefully. Moreover, an operator may not notice that the clutch mechanism is switched to the manual operation side and may not be able to perform image taking as desired.
Furthermore, if an operator operates the manual ring manually when the clutch is switched to the motor drive side, the operation of the manual ring will be heavy due to the application of the rotational load of the motor. However, the operability may be lowered if the operator has to switch to the manual operation side manually by the clutch mechanism each time to obtain a good operation sensation.
For the problem that the correspondence between the lens position and the position to which an operating member is moved (rotated) by motor drive is not matched, a method, wherein a position detector is provided for detecting the position of the manual ring, information indicating the respective positions within the movement (rotation) range of the manual ring are stored in a microcomputer in advance during an initial setting step prior to the start of image taking, etc., and positional control of the lens is performed so as to correspond with these position information, may be considered.
However, if a potentiometer, etc., is used as the position detector for detecting the position of the manual ring, since the output voltage from the position detector will vary due to the temperature drift phenomenon, deviation may occur between the position of the manual ring stored during initial setting and the actual position of the manual ring. In this case, the focal length and the in-focus distance indicated by the manual ring may deviate from the actual focal length and in-focus distance of the optical system.